Typewriting machine



1511.4, 1938. w. F. HELMOND 2,104,432

TYPEWRITING MACHINE Filed Nov. 1, 1955 2 Sheets-Sheet 1 Jan. 4, 1938. w. F. HELMOND 2,104,482

TYPEWRITING MACHINE Filed NOV. 1, 1935 2 Sheets-Sheet 2 ATTLJRZZ reams it 4, 193a umrso STATES 2,104,482 TYPEWBITING MACHINE William F. Helmond,

signor to Underwood New York, N.

West Hartford, Conn., as-

Elliott Fisher Company,

Y.., a corporation of Delaware Application November 1, 1935, Serial No. 47,731 Claims. (Cl. 197-188) This invention relates to sound-deadening devices for typewriting machines and other utensils having sheet-steel or other weldable workedmetal parts.

. Primarily the intensity of the sound depends upon the amplitude of the vibrations, and the prolongation or repetition of soundby reflection or reverberation is resonance. The impact of the ewe-bars upon the platen of a typewriter sets up vibrations and resonance proportional to the form and structure of the several essential parts of the machine. To choke the vibration, particularly that of sheet-metal parts, is therefore effective to deaden the sonorousness of these parts. 7

An object of the present invention is to improve the construction oi the sonorous parts, and I more especially of the sheet-metal parts in a typewriter, so as to reduce vibration to a mini- 20 mum; more especially so to improve the con-- struction of the mask in a portable typewriting machine, so to improve the construction 0! the paper-table in a typewriter, so to improve the construction of the stop-ring i'or type-bars, so to improve the construction of the platen, so to 11m prove the construction of panel plates, and so to improve the construction of other parts, devices or elements, directly or indirectly connected with any typewriter, it being obvious that the reduc- 39 tion of sound and the elimination of sonorousness are important utilities in this art.

Another object of the invention is to eliminate the sonorousness oi sheet-metal parts in any utensilutillzing steel or other weldabie worked 35 metal, preferably sheet-steel, and more particularly where, during the operation of such utensils, there is a tendency to set up vibrations.

Other objects will appear as the description proceeds.

To deaden or mufie the sound of a typewriter, sheet-metal parts have been lined internafly with linoleum, ielt, rubber, asbestos, cork, and sometimes with intermediate layers of lead. In any or all of these constructions, it is obvious that the wall formed by the sheet-metal and its sound-deadening lining is many times thicker than is the sheet-metal alone, and also that the lining or interlining adds nothing to the strength oi the sheet-metal Wall.

A feature of the present invention is to lock together two similar pieces of sheet metal, but of piles of less than the usual thickness of each, surface upon surface throughout, positively by the use of spot-Welding, whereby vibrations in either piece are immediately deadened or choked by those in the other piece. Experimentation has revealed that for a complete and satisfactory deadening eiiect the surfaces of the contiguous sheets of metal must be positively locked by spotwelding, so that at definite places the contiguous pieces of sheet-metal are integrated one with the other, particularly at the loci of the maximum amplitude of vibration of said pieces. Important consideration attaches to the construction of spot-welding similar pieces having frac- 10 tions of the usual thickness, so that the resulting non-vibrating or sound-deadening unit is identical in size or thickness with the part or piece for which it is substituted, thereby eflecting a great saving in cost in introducing this improved sound-deadening construction throughout a typewriter, or in any other utensil made of weldable worked metal, the sound of operation being decreased proportionally more in each instance when and as this improved sound-deade'ning device is used in additional places in the typewriter or utensil. I

In spot-welding one piece of sheet-metal or other weldable worked metal upon another piece of sheet-steel, in order to substantially eliminate the sound, it is important that the sonorousness of one plate be approximately the same as that ol the other. Plates oi the same .composition, size, formand thickness are substantially the same in sonorousness. Variation in the relationships in any of these elements varies the sonorousness. A convenient form of plate is one of the same size, form, thickness and material as the other plate, so that when the two plates of steel or other weldable worked metal 35 are spot-welded together, the sonorousness oi the plates is substantially identical so that when integrated by spot-welding at the loci of the maximum amplitude of vibrations, the sonorousness of the one plate is entirely checked or deadened by the sonorousness of the other plate. It is obvious that this invention is applicable to typewriters or other metal utensils having frames of steel or other weldable worked metal, preferably sheet-steel.

By spot-welding along axial or medial lines of the adjacent contiguous small-area pieces of sheet-metal a good result is obtained with a minimum of the spot-welding operations. In such pieces that have a relatively small area spotwelding along an axial or medial line effectively integrates the contacting pieces at or in the zones of maximum potential amplitude of vibration, and so therefore more efiectively binds the surrounding surfaces one upon the other in direct propor- 55 tion tothe increased tendency of the pieces to vibrate caused by blows or impacts in any part of the typewriter, or other utensil, comprising metal elements in combination with one another. In other words, the spot-welding at the axial or medial lines integrates the two pieces at or in the central zone of these-pieces and so positively and completely chokes off all vibration or motion of the two pieces relatively to one another in the surrounding area, thereby completely choking or deadening the sonorousness of either of the integrated pieces of sheet-metal. Or again to express it popu1ar1y, by increasing the trouble of sonorousness by splitting the sheets of metal, the trouble of one sheet is killed by the trouble of the other byintegrating the contiguous sheets by means of spot-welding. When, however, the

. sheets are cut to, form extensions, spot-welding substantially centrally of the extensions is desirable for good results in choking the sonorousness, and when surfaces are in a different plane from other parts of the sheets, spot-welding substantially centrally in the different plane surfaces is desirable for the effective elimination of sonorousness.

Other features and advantages will hereinafter appear.

In the accompanying drawings,

r Figure 1 is a perspective view of a mask for portable typewriter, with parts cutaway in a side and rear wall to show the improved sounddeadening construction.

Figure 2 is a perspective view of'the front cover of a. portable typewriter.

Figure 3 is a side elevation of a portable machine, with some parts removed and other parts shown in section where they embody the improved sound-deadening construction.

Figure 4 is an isometric view of a paper-table of the sonorousness-deadening construction.

Figure 5 is an isometric view with parts of the top cover, and the front cover broken away to show the embodiment of the invention in an Underwood noiseless typewriter.

Figure 6 is a side elevation, partly in section, showing a typebar in engagement .with the cushioned stop-ring embodying the improved sound-deadening construction.

Figure 'I'is a front view of the stop-ring.

Figure 8 is a cross-section of the platen with a juxtaposed type-bar head, showing the improved sound-deadening construction both faced and backed by rubber.

Figure 9 shows an edge view or section of a spot-welded noiseless plate.

Figure 10 is a plan view of the platen shown in Figure 8, but with a part broken away, and showing a lengthwise section.

Figure 11 is a. view similar to Figure 10, but with the outer rubber platen-surface stripped off.

Figure 12 is an isometric inside view of the side frame of an Underwood standard typewriter, showing a panel for closing the opening in the side frame, parts of the frame and the panel being broken away.

In Figure 1, a sheet-metal mask i I of an Underwood portable typewriter, as shown in patent to Lentz, No. 1,901,398, of March 14, 1933, is formed of an inner ply i 2 and an outer ply E3, the plies being sheet-metal, of steel or other weldable worked metal, and having identical form, size,

material and thickness, and being spot-welded 'together at a plurality of loci H. An inwardlyturned flange l5 forms the topedge, and at the inreaching lugs IS. The loci of the spot-welding M are in substantially central or medial zones of each flat plate, except in the upward side extensions, where additional spot-welding is placed substantially centrally or medially in the area of the upward side extensions. The loci of the spotwelding H are determined by the loci of the maximum potential amplitude of vibration in the plies, and in' metal sheets of identical form, size, material and thickness, such loci are usually in central or medial zones. In sheets of narrow width, by so locating the spot-welding, a single row of fewer spots suflices completely to deaden the vibrations and eliminate the sonorousness, but where there are protuberances in edges of the sheets the location of spot-welding in the protuberances centrally or medially thereof effectively chokes or nullifies the vibrations and so eliminates the sonorousness thereof.

In Figure 2, a sheet-metal front cover I! of an Underwood portable typewriter is formed of an inner ply i2 and an outer ply I 3, the piles being sheet-metal, of steel or other weldable worked metal, and being spot-welded together at the loci l4. It will be noted that the top surfaces of the front cover I! lie in a plane or planes substantially at right angles to the plane formed byto receive screws 2i passed through apertures in the lugs I6, and the latter by the inwardlyturned lugs iiltapped to receive the screws 2! passed through apertures in the front cover, and the rear wall of the mask i l is also secured to 4 the rear wall 53 of the frame l8 by the screws M. A carriage 22 reciprocates with reference to the frame l8 by means of the rear carriagerail 23 and the rear frame-rail 24 and interposed anti-friction elements or balls 25 and the front carriage-rail 26 and the front frame-rail 27 and interposed balls 25, and has the usual roll platen 28 carried thereon across the path of movement of type-bars 29. A paper table 30 embodying the sonorousness-choking invention is mounted on the carriage by means of apertured pendent lugs 3| pintled upon supports 32. Figure 4 clearly shows the inner ply i2 and the outer ply it of the paper table 30, the loci It of the spot-welding being in zones coincident with the lengthwise lines running through the zones of the maximum amplitude of vibration, or' the zones of the maximum potential sonorousness.

In Figure 5 is shown an Underwood noiseless typewriter having a top-cover 33, a part broken away at the front to show the inner ply i2 and the outer ply l3 which arespot-welded at the loci H of the zones of the maximum amplitude of vibration of the piles, and also having a. front cover 38, a part similarly broken away to show the outer ply i3 and the inner ply I2, and on which are loci M of the spot-Welding. The topcover 33 and the front cover 34 are secured to the frame or casing 35 by screws 38.

g In Figure 6, the usual metal segment 81 carries the segment rod 88 on which is mounted the Reference to type-bar tii adapted to strike the platen 28, and the stop-ring 39, which has a central rid e 40, backed by soft rubber 4!; the stop-ring 39 and its rubber backing 4i being secured to the segment 31! by means of the screws 42. The stopring 38 embodies the sonorousness-destroying improvements in inner ply l2 and outer ply l3 spot-welded together at the loci indicated at l4. It is apparent that the type-bar 29 intercepts the stop-ring 39 before striking the platen and that the elasticity must suffice to quickly and eiIectively return the type-bar to its initial position, so that the elimination of sonorousness in the stop-ring 39 contributes substantially to 'complete elimination of sonorousness from the typewriter.

In Figures 8, l0, and 11, a platen 28 has the usual outer rubber cylinder 44, an inner softrubber cylinder 45, and an intermediate metal cylinder 43 embodying an inner cylinder-i2 and an outer cylinder I3 spot-welded together at the loci i4 indicated in Figure 11, that is, at points selected most effectively tocheck the sonorous vibration of said cylinders,

In Figure 12, the side-frame 46 of an Underwood standard typewriter has a large opening 41 which is closed by a removable panel 48 which is formed of an inner ply I! of sheet-metal and an outer ply l3, the two plies being spot-welded together in a central or medial zone defined by the loci 14. The frame is provided with an upper flange 49 formed to provide a recess 50 for the passage of the typewriter carriage and having a pendent side in which are mounted screws 52 passing through tapped holes in the removable panel 48 and securing said panel 48 in the opening 41 and fast against the perpendicular wall of the pendent side 5|.

It is now clear that by utilizing my improved device for eliminating sonorousness from the sheet-metal parts of a typewriting machine, I

have susbtantially eliminated sonorousness from the entire machine, and it is further clear that my invention is similarly meritorious and useful in eliminating sonorousness from any other utensils having sheet-metal parts of steel or other weldable worked metal.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, I claim:

1. In a noisy typewriter, a plurality of workedmetal muting laminations, having substantially the same sonorousness, and having their contiguous surfaces in contact one with the other, and being spot-welded together within the zone of maximum amplitude of vibration of said laminations, said laminations having free edgeportions.

2. In a noisy typewriter, a plurality of workedmetal muting laminations, having substantially the same sonorousness, and having their coni uous surfaces in contact one with the other,

welded together at and being spot-welded together within the zone of maximum amplitude of vibration of said laminations, said laminations having free edgeportions, and also being bodily spot-welded together at the coincident loci of maximum amplitude of vibration of said laminations.

3. In a noisy typewriter, a plurality of workedmetal muting laminations, having substantially the same sonorousness, and having their contiguous surfaces in contact one with the other, and being spot-welded together within the zone of maximum amplitude of vibration of said laminations, said laminations having free edgeportions, and also being bodily spot-welded together substantially along a medial or central line of said laminations.

4. In a noisy typewriter, a muting device including, in combination, two contacting laminations of metal spot-welded together, one lamination being sufllciently large substantially to choke the sonorousness of the other.

5. In a noisy typewriter, a concussion-muting device in the form of a paper-table comprising similar laminations of metal spot-welded together at a plurality of points within the zones of the maximum amplitude of vibration of said laminations. I

6. In a typewriter, having noisy metal typebars, a muting device in the form of a stop-ring for said type-bars, comprising two similar segmental laminations of metal spot-welded together at a plurality of points within the zones of maximum amplitude of vibration of said laminations.

7. In a typewriter, a platen against which types strike, said platen comprising an outer cylinder of hard rubber, an inner cylinder of soft rubber, and an intermediate cylinder formedof two contacting shells of metal spot-welded together at a plurality of points to mute the sonorous vibration of said cylinders at the type-concussions.

8. In a typewriter, a platen against which types strike, said platen having a core in the form of a tube formed of contacting metal shells, one closely fitting within the other, said shells being spot-welded together to mute the type-concussions, and a soft rubber cylinder upon said core and provided with a wearing jacket.

9. A tubular core for a typewritereplaten havingconcussive metal types, in the form of cylindrical shells of'worked metal fitting one within the other with free edge-portions and spot-weld ed together to mute the type-concussions.

' 10. A typewriter provided with a keyboard and having metal types and a letter-feeding carriage which make noisy concussions at the operation of the keys and the carriage,-said typewriter having a member for muting the noise of the concussions, said'muting member being built up of similar sheet-metal laminations whose edgeportions are free, but whose bodies are spotscattered points.

WILLIAM F. HELMOND. 

